It has become common practice for businesses to place automated telephone calls in order to deliver messages to phone subscribers at called locations, such as telephones. Over the years, these automated systems have had to become more and more sophisticated, particularly because of the increasing complexity of the telephone network. In the early days of automated calling, when the called telephone started to ring (after ringing was detected) the automated system began playing the desired message. This message was played over and over and over again until either an answering machine received it or the called party, after hearing the message, hung up. One problem was that the automated calling system did not know if the message was delivered, and if delivered, did not know if a live person actually received the message. Such systems could not distinguish between a live answer or an answering machine.
Numerous systems have been directed to answer supervision and detection. Some of these are U.S. Pat. No. 4,405,833, Cave, et al., issued Sep. 20, 1983, entitled “Telephone Call Progress Tone and Answer Identification Circuit,” U.S. Pat. No. 4,696,031, Freudberg, et al., issued Sep. 22, 1987, entitled “Signal Detection and Discrimination Using Waveform Peak Factor,” U.S. Pat. No. 4,979,214, Hamilton, issued Dec. 18, 1990, entitled “Method and Apparatus For Identifying Speech in Telephone Signals,” U.S. Pat. No. 5,311,588, Polcyn, et al., issued May 10, 1994, entitled “Call Progress Detection Circuitry and Method,” U.S. Pat. No. 5,371,787, Hamilton, issued Dec. 6, 1994, entitled “Machine Answer Detection,” U.S. Pat. No. 5,671,272, Cotreau, issued Sep. 23, 1997, entitled “Current Mode Ring Trip Detector,” U.S. Pat. No. 5,241,584, Hardy, et al., issued Aug. 31, 1993, entitled “Response Time Evaluation Unit,” U.S. Pat. No. 6,483,897, Millrod, issued Nov. 19, 2002, entitled “Method and Apparatus for Answering a Telephone with Speech,” U.S. Pat. No. 6,321,194, Berestesky, issued Nov. 20, 2001, entitled “Voice Detection in Audio Signals,” U.S. Pat. No. 5,023,906, Novas, issued Jun. 11, 1991, entitled “Method for Monitoring Telephone Call Progress,” U.S. Pat. No. 4,640,990, Kawade, et al., issued Feb. 3, 1987, entitled “Telephone Answering Apparatus Having Two Integrators of Different Time Constants,” and U.S. Pat. No. 4,356,348, Smith, issued Oct. 26, 1982, entitled “Techniques for Detecting a Condition of Response on a Telephone Line.” In addition, many systems have been directed to automated call generation. Some of these are U.S. Pat. No. 5,982,858, Carter, et al., issued Nov. 9, 1999, entitled “System for Providing Automatic Voice Messaging in a Digital Network Environment,” U.S. Pat. No. 5,661,790, Hsu, issued Aug. 26, 1997, entitled “Call Back Service for a Regulatory Restrictive Area,” U.S. Pat. No. 5,546,442, Foladare, et al., issued Aug. 13, 1996, entitled “Method and Apparatus for Use in Completing Telephone Calls,” and U.S. Pat. No. 5,425,091, Josephs, issued Jun. 13, 1995, entitled “Method and System for Providing an Automatic Customer Callback Service.” Theses patents are representation of the systems available and not an exhaustive list.
Prior to answering machines it was relatively easy to know if a live person answered. A call was either in a network processing state (ringing or busy) or in an answered state, and without answering machines an “answered ” call had to be live. As soon as voice was detected, the message was played. Voice was determined using several techniques, some of these included detection of the number of frequencies of the signal being returned from the called line, by the power levels received, or by combinations thereof. Again, if there was any “voice” signal, then it was a live person answering.
As answering machines have become more prevalent, discrimination between live answer and machine answer has become more difficult. Typically, live voice is a short burst, such as “Hello”, while an answering machine would deliver a longer message. Thus, algorithms to discriminate between a live answer and a machine answer are typically time based. This works well for home calling, but not so well for situations where a receptionist answers the telephone and says, “Hello, this is XYZ, who do you wish to speak with?”, sometimes even working a sales pitch into the greeting. Thus, a timed approach to answer discrimination does not work well in all environments. To know with some degree of certainty whether a call is being answered live or by machine, existing systems fall short.
Another problem with a timed approach to answer discrimination is that when a called party answers the phone there is silence. While the calling system is trying to decide (based on answer greeting length) whether or not a live answer has occurred. From the called party's perspective, there is a silence or pause of varying length, and the called party knows it is a machine calling and often simply hangs up. The caller has said “Hello” and the system is waiting to see if that is the last thing the caller is going to say. The system looks for the ½ to 1 second of silence following the initial greeting. If the automated system “hears” silence following the initial greeting, then it knows that a live person has answered and starts playing it's message.
Some answering systems have interposed an automatic layer between the caller and the called party. Existing systems, because of the length of the message, would determine that this is an answering machine and act accordingly, thereby missing an opportunity to connect for a live person. For example, a call director might answer the can and say, “Please push 1 for John and 2 for Bill”.
There are numerous situations where it is important for a calling system to determine if a message has been delivered, and if so, to whom and when. Such systems must also know if the message has been delivered live or if it has been left on an answering device. Systems that cannot accurately discriminate between the various answer scenarios are not useful in such situations.